Approach:
Candidate avirulence genes will be identified from gene expression studies or by analysis of genomic sequences of Puccinia triticina. Candidates will be tested for ability to induce hypersensitive necrotic responses on resistant wheat varieties. An association mapping population representing diverse hard winter wheat germplasm will be tested in the field and in the greenhouse for resistance to the three rusts. Lines will be genotyped using a large set of SNP markers. Genomic regions associated with lower mean disease scores will be further investigated. Mapping populations will be developed using the doubled haploid (DH) or the recombinant inbred line (RIL) approach for native and exotic sources of resistance to leaf rust, stripe rust, and stem rust.